EMBRYOLOGY AND SYSTEMATICS OF EUPHORBIACEAE SENS LAT - A REVIEW AND PERSPECTIVE

Based on a literature survey, we present a review of the embryology of Euphorbiaceae sensu Webster (with about 8,000 species in five subfami lies), which are one of the largest and most diversified families and have often been considered heterogenous. Nearly 40% of over 110 public ations available for the whole family is concerned with a single genus Euphorbia, so that the current level of our knowledge on the embryolo gy of Euphorbiaceae is very poor. Nevertheless we found that, contrary to a conclusion recently published by other authors, available inform ation does not provide evidence to support a monophyly of Euphorbiacea e. Our analysis further suggested that only the following five of over 50 embryological characters of ovules and seeds are likely to be usef ul for comparison between and within subfamilies: (1) the presence or absence of vascular bundles in the inner integument; (2) whether the i nner integument is thick or thin (probably useful only in Phyllanthoid eae); (3) whether ovules or seeds are pachychalazal or not; (4) whethe r seeds are arillate or not; (5) whether an exotegmen is fibrous or no t. On the basis of these five characters, a consistency and diversity of individual subfamilies was discussed. The need of further extensive studies on the five characters using herbarium specimens, particularl y in genera of Phyllanthoideae, Oldfieldioideae and Acalyphoideae, was also discussed.